1. Field of the Invention
The present invention relates to a light-guiding module, and in particular to a light-guiding module provided in an optical touch screen.
2. Description of Related Art
Recently, with the development of a touch screen, a user can input commands by using a touch pen or even his/her finger to directly tip the touch screen, thereby replacing the traditional input operation of keys or buttons. Thus, the touch screen has become popular recently. When the user tips an icon on the touch screen, a touch feedback system on the screen is activated based on preset programs so as to generate a vivid picture on the screen.
There are several categories of touch screens, such as resistance type, capacitance type, acoustic-wave type, optical type and etc. The optical touch screen utilizes a principle of receiving or intercepting light. A touch intercepts the light, and a light receiver can determine the position at which the light is intercepted, thereby generating a predetermined action. As shown in FIG. 1, the optical touch screen includes a light-guiding module 11 and a light receiver 12 which are arranged on a liquid crystal display 13. The light emitted by light-emitting diodes 111 in the light-guiding module 11 is reflected by light-guiding strips 112 to form a touch space. When a finger or object is located in the touch space to intercept the light, the light receiver 12 can determine the position of the finger or the object with respect to the touch space.
However, when the light emitted by the light-emitting diode 111 enters the light-guiding strips 112 to form a light L, the brightness of the light L is higher if the distance between the light L and the light-emitting diode 111 is lower. Further, the brightness of the light L is lower if the distance between the light L and the light-emitting diode 111 is larger. Light-guiding microstructures (not shown) are provided in the light-guiding strips 112 to refract the light. Thus, the brightness of the light near the light-guiding microstructures is larger. As a result, the light throughout the touch space is not uniform, so that the optical signals received by the light receiver 1 are not uniform either, which may cause an erroneous determination easily. To solve this problem, a common solution is to adjust the parameters of the light receiver 12, which undesirably causes the inconvenience in production. If the adjustment is improper, an erroneous determination is also generated, which results in unqualified products.
Thus, it is an important issue for designers and manufacturers in this art to improve the structure of the light-guiding module to generate uniform light.
In order to overcome the problems of the above-mentioned socket, the present inventor proposes a novel and reasonable structure based on his delicate researches and expert experiences.